Persistent underwater monitoring or surveillance, such as in antisubmarine warfare (ASW) or antiterrorism monitoring, typically relies on sonar sensors deployed on the seafloor or towed by surface ships or submarines. Persistent seafloor sensors today may be connected by a cable to a ship or shore station. Access to some regions of littoral seas for such purposes may, however, be denied and/or the cost of widespread persistent monitoring by submarine may be prohibitive or unsustainable. As a result, the U.S. Navy has been developing detached array monitoring systems with battery caches and tethered radio buoys for connectivity. Seafloor electronics devices are, however, often at risk of disturbance or damage by currents or by equipment (e.g., fishing nets) and other objects moving over the seafloor. Sensors that are easily dislodged or damaged are clearly undesirable for persistent or undetected monitoring.